CN103368367A - Loop-current elimination method for inverters with dc sides in parallel suitable for photovoltaic power generation - Google Patents
Loop-current elimination method for inverters with dc sides in parallel suitable for photovoltaic power generation Download PDFInfo
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- CN103368367A CN103368367A CN 201210099127 CN201210099127A CN103368367A CN 103368367 A CN103368367 A CN 103368367A CN 201210099127 CN201210099127 CN 201210099127 CN 201210099127 A CN201210099127 A CN 201210099127A CN 103368367 A CN103368367 A CN 103368367A
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- inverter
- inverters
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- common mode
- loop
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention aims at providing a method for isolating micro faults for dc links of inverters in parallel connection, and eliminating loop current between the dc links of the inverters.
Description
Technical field
The present invention relates to a kind of inverter loop current null method that is applicable to the DC side parallel of photovoltaic generation, be mainly used in the elimination of the dc loop-current between the combining inverter in parallel.
Background technology
The large-scale photovoltaic power plant needs large capacity inverter to improve generating efficiency.And being subjected to the restriction of switching device capacity, the capacity of single inverter may not meet the demands, and just needs this moment inverter parallel to improve power system capacity.The inverter of DC side parallel refers to that two or more inverters uses public DC link, and direct voltage is reverse into alternating voltage, electric energy is sent into respectively the convertor assembly of electrical network.Do not have circulation flow path between this parallel way AC refers to, main circulation is in the DC side of parallel connection.When single inverter worked alone, proper if control algolithm relates to when transient fault occurs, inverter can recover normal performance after fault disappears; Only in failure process, may there be the fluctuation of DC link.When many inverters were worked simultaneously, when an inverter generation transient fault, when causing direct voltage to descend, because the direct voltage link is in parallel, other operations of several also can be affected, and can cause equally the hydraulic performance decline of parallel system.In the situation that extreme, many inverters interact and impact, and transient fault may cause the shutdown of whole parallel system.On the other hand, because the inconsistent circulation that causes of the direct voltage on the shunt chopper electric capacity may impact the normal operation of switching device, reduce its life-span.Therefore, need to be for this situation, measure reasonable in design, the small fault that prevents the single inverter DC link exerts an influence to other inverter of parallel connection.
Summary of the invention
For above-mentioned background, the objective of the invention is provides a kind of method to the small fault isolation for the DC link of the inverter of parallel connection, eliminates the circulation between the inverter DC link.
The objective of the invention is to be achieved through the following technical solutions:
(1) between the inverter of parallel connection, increases common mode transformer.The starting point of design common mode transformer is: in the time of the mutual balance of DC link of the inverter of parallel connection, do not have pressure drop on the inductance; When DC link dynamic inconsistent, the common mode transformer inductance is the impact of isolated DC voltage differences to a certain extent;
(2) on this basis, to the secondary current of common mode transformer, namely the circulation of DC link carries out FEEDBACK CONTROL.Increase simultaneously the voltage control link, to improve the dynamic property of system;
(3) target of control is that the inverter DC link is carried out to a certain degree isolation: when the balance of voltage on the inverter electric capacity, pressure drop is controlled as zero on the common mode transformer; When certain inverter of parallel connection causes the DC link fluctuation because of some reason (such as fault); utilize controller and common mode transformer to produce opposite fluctuation; eliminate the circulation between the DC link; chop failure path off, prevent other normal inverters be subject to occuring transient fault inverter impact and cause the shutdown of whole system.After the transient fault disappearance, behind the fault inverter performance recovery, the pressure drop of common mode transformer secondary reverts to zero.
Compared with prior art, good effect of the present invention is:
(a) to the DC link of the inverter of DC side parallel, isolate, reduced the circulation between the inverter DC link;
(b) the DC link fluctuation of single inverter compensated, chop failure path off, prevent that this inverter from affecting the inverter of other normal operations.
Description of drawings
Fig. 1 is the inverter topology figure of the DC side parallel of the controlled common mode transformer of band of the present invention, take two parallel connections as example.
Fig. 2 is the schematic diagram of the former limit of common mode transformer control system, take two parallel connections as example.
The above only is preferred technical scheme of the present invention, for those skilled in the art, without departing from the inventive concept of the premise, can also make some improvements and modifications, and these improve with retouching and also can be considered as within protection scope of the present invention.
Claims (2)
1. inverter loop current null method that is applicable to the DC side parallel of photovoltaic generation is characterized in that:
(1) between the inverter of parallel connection, increases common mode transformer;
(2) secondary current of common mode transformer carried out FEEDBACK CONTROL;
(3) target of control is to eliminate circulation, and the voltage on the electric capacity of shunt chopper can be inconsistent.
2. a kind of inverter loop current null method that is applicable to the DC side parallel of photovoltaic generation that requires such as right 1 is characterized in that: to the two-stage FEEDBACK CONTROL of common mode transformer secondary current, suppress system's circulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201210099127 CN103368367A (en) | 2012-04-06 | 2012-04-06 | Loop-current elimination method for inverters with dc sides in parallel suitable for photovoltaic power generation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201210099127 CN103368367A (en) | 2012-04-06 | 2012-04-06 | Loop-current elimination method for inverters with dc sides in parallel suitable for photovoltaic power generation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103368367A true CN103368367A (en) | 2013-10-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201210099127 Pending CN103368367A (en) | 2012-04-06 | 2012-04-06 | Loop-current elimination method for inverters with dc sides in parallel suitable for photovoltaic power generation |
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| CN (1) | CN103368367A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104362843A (en) * | 2014-10-24 | 2015-02-18 | 阳光电源股份有限公司 | Parallel inversion system, and shutdown control method and shutdown control device for parallel inversion system |
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2012
- 2012-04-06 CN CN 201210099127 patent/CN103368367A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104362843A (en) * | 2014-10-24 | 2015-02-18 | 阳光电源股份有限公司 | Parallel inversion system, and shutdown control method and shutdown control device for parallel inversion system |
| CN104362843B (en) * | 2014-10-24 | 2017-06-13 | 阳光电源股份有限公司 | Parallel inverter system and its halt control method and stop control apparatus |
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| C06 | Publication | ||
| PB01 | Publication | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20131023 |